Fluoropolymer films have long been used in applications where the finished film is exposed to ultraviolet light. For example, poly(vinyl fluoride) films are often used as a protective surface on building materials such as aluminum and poly(vinyl chloride) house siding. To prevent degradation, by the ultraviolet light, of film itself and either a bonding layer or a substrate beneath the film, screeners have often been incorporated into the films.
In the past, poly(vinyl fluoride) films were typically used which had been molecularly oriented in one or both of the machine and transverse directions. More recently, however, unoriented films have been needed for protective applications in which a high degree of clarity was also desired. It was found that the ultraviolet light screeners, of the types and in the concentrations previously used in poly(vinyl fluoride) films, did not provide the optical clarity required for certain decorative applications.